Keep in mind that as you fly and the current increases in your wiring harness the amount of magnetic interference and the distance the magnetic field extends beyond the wire also increases.
We believe that the reason some people are having poor performance with Position Hold is simply this type of current induced magnetic interference. The proximity of wiring to the on-board magnetometer (compass) of the HoverflyGPS can cause poor compass readings.
One solution to this issue is to use an external magnetometer mounted away from the wiring and electronics. We also continue to monitor the market for improvements in GPS antenna technology, and from time to time we may introduce or suggest new antenna models for use with the HoverflyGPS.